From 314b4778ed579f29b6d46ba90dbf31314c13805f Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Tue, 21 Jun 2011 07:34:37 +0000 Subject: net: dcbnl, add multicast group for DCB Now that dcbnl is being used in many cases by more than a single agent it is beneficial to be notified when some entity either driver or user space has changed the DCB attributes. Today applications either end up polling the interface or relying on a user space database to maintain the DCB state and post events. Polling is a poor solution for obvious reasons. And relying on a user space database has its own downside. Namely it has created strange boot dependencies requiring the database be populated before any applications dependent on DCB attributes starts or the application goes into a polling loop. Populating the database requires negotiating link setting with the peer and can take anywhere from less than a second up to a few seconds depending on the switch implementation. Perhaps more importantly if another application or an embedded agent sets a DCB link attribute the database has no way of knowing other than polling the kernel. This prevents applications from responding quickly to changes in link events which at least in the FCoE case and probably any other protocols expecting a lossless link may result in IO errors. By adding a multicast group for DCB we have clean way to disseminate kernel DCB link attributes up to user space. Avoiding the need for user space to maintain a coherant database and disperse events that potentially do not reflect the current link state. Signed-off-by: John Fastabend Signed-off-by: David S. Miller --- include/linux/rtnetlink.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/rtnetlink.h') diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index bbad657a3725..c81226a9a35c 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -585,6 +585,8 @@ enum rtnetlink_groups { #define RTNLGRP_PHONET_IFADDR RTNLGRP_PHONET_IFADDR RTNLGRP_PHONET_ROUTE, #define RTNLGRP_PHONET_ROUTE RTNLGRP_PHONET_ROUTE + RTNLGRP_DCB, +#define RTNLGRP_DCB RTNLGRP_DCB __RTNLGRP_MAX }; #define RTNLGRP_MAX (__RTNLGRP_MAX - 1) -- cgit v1.2.3 From d8bf4ca9ca9576548628344c9725edd3786e90b1 Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Fri, 8 Jul 2011 14:39:41 +0200 Subject: rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check Since ca5ecddf (rcu: define __rcu address space modifier for sparse) rcu_dereference_check use rcu_read_lock_held as a part of condition automatically so callers do not have to do that as well. Signed-off-by: Michal Hocko Acked-by: Paul E. McKenney Signed-off-by: Jiri Kosina --- include/linux/rtnetlink.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'include/linux/rtnetlink.h') diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index bbad657a3725..27576aa05e8c 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -758,8 +758,7 @@ extern int lockdep_rtnl_is_held(void); * or RTNL. Note : Please prefer rtnl_dereference() or rcu_dereference() */ #define rcu_dereference_rtnl(p) \ - rcu_dereference_check(p, rcu_read_lock_held() || \ - lockdep_rtnl_is_held()) + rcu_dereference_check(p, lockdep_rtnl_is_held()) /** * rtnl_dereference - fetch RCU pointer when updates are prevented by RTNL -- cgit v1.2.3